Furnace for low and high heat value fuels



April 1966 J. F. KLOECKER 3,244,220

7 FURNACE FOR LOW AND HIGH HEAT VALUE FUELS Filed Jan. 22, 1964 1 4Sheets-Sheet 1 April 5, 1966 J. F. KLOECKER 2 3,244,220

FURNACE FOR LOW AND HIGH HEAT VALUE FUELS Filed Jan. 22, 1964 4Sheets-Sheet 2 INVENTOR FIGZ- ram/e4 W WWW) I April 1966 J. F. KLOECKER3,244,220

FURNACE FOR LOW AND HIGH HEAT VALUE FUELS Filed Jan. 22, 1964 4Sheets-Sheet 3 lNVEN TOR.

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United States Patent ()fiice 3,244,220 Patented Apr. 5, 1966 3,244,220FURNACE FOR LOW AND HIGH HEAT VALUE FUELS John F. Kloecker, Erie, Pa.,assignor to Erie City Iron Works, Erie, Pa., a corporation ofPennsylvania Filed Jan. 22, 1964, Ser. No. 339,369 Claims. (Cl. 15811)Burners for burning fuels of low unit heat content such as blast furnacegas, gas turbine exhaust, wood waste, should embody a high degree ofturbulence and should confine the heat of combustion within a limitedspace to assure rapid heating of the fuel and air mixture to theignition point. The present invention accomplishes these objectives bythoroughly mixing fuel and air and burning this mixture in a refractorylined furnace. In the case of extremely low heat value fuels somesupplementary fuel may be required to support combustion. This inventionprovides means for introducing this supplementary fuel to the mass ofburning fuel within the ignition chamber of the burner. Any gaseous fuelor fuel burned in suspension is suitable in this burner either asprimary fuel or as supplementary fuel to support combustion.

This invention is best described by referring to the accompanyingdrawings as follows:

FIGURE 1 is a longitudinal section through the burner.

FIGURE 2 is a section through the air register on line 2-2 of PEG. 1.

FIGURE 3 is a section through the burner throat tile along line 3-3 ofFIG. 1.

FIGURE 4 is a section on line 44 of FIG. 1 showing the primary fuelplenum chamber, the discharge ports, air passages, and combustionchamber lining.

FIGURE 5 is an adaptation of a pulverized coal discharge nozzle forfiring supplementary fuel.

FIGURE 6 shows an alternate supplementary fuel gas burner arrangementplaced centrally in burner throat.

FIGURE 7 isan alternate arrangement showing a square shaped combustionchamber. I

During operation, a low heat value gaseous fuel such as blast furnacegas, gas turbine exhaust, or others, enters the burner through a ductattached to flanged opening 1 communicating with a gas plenum chamber 2(FIG. 4), extending completely around the combustion chamber whichextendsaxially from the front of the burner. This gas may be cool orextremely hot. Gas, at equal pressure in the plenum chamber, then entersth'ecombustion chamber 3 through angularly spaced fuel ports 4. Thedegree of angularity of'these ports with the center line of the chambercan be varied to produce varying degrees of rotation in the combustionchamber.

Air for combustion is controllably introduced through flanged connection5 which communicates with air plenum chamber 6 which extends completelyaround the combustion chamber. Air in plenum chamber 6 cools the steelwrapper sheet 7 of the combustion chamber which is in contact with andsupports combustion chamber lining 8. From the air plenum chamber, airtravels forwardly through passageways 9 and 10 formed between wrappersheet 7 and concentric air duct plate 11 which forms the inside of gasplenum chamber 2. Air passes around and between fuel ports 4, whosepassage is defined by plates 12 and 13. In traversing this passage, theair cools plates 7, 11, 12 and 13, and refractory linings 8 and 14.Refractory linings 8 and 14 may be of any type suitable for thetemperature encountered. Refractory shapes may be supported by beingpart of a complete circle as shown, or may be attached to wrapper sheet7 by other means. Refractory 14 between ports 4 may be shapes, plasticor castable, held in position by anchors 15 or other suitable Aftercooling the combustion chamber during its forward passage throughpassageways 10, the air is discharged in a heated condition in to theburner wind-box 16 at the front of the burner. Air movement from thewind-box may take one or more of three passages to the combustionchamber. Normally, when burning low heat value gas with a minimum ofsupplementary fuel, all of the combustion air flows through the burnerregister 17 (FIG. 2), where it receives a rotary motion from vanes 18.This air passes through burner housing 19, and flows throughsupplementary fuel gas manifold 20, and mixes with gas being dischargedthrough ports 21. If oil is the supplementary fuel, the air mixes withthe discharge froin burner tip 22. If a center fired gas burner (FIG. 6)is used, gas is discharged through ports 23. Pulverized coal may beintroduced through nozzle 39 (FIG. 5). Supplementary fuel and air forcombustion of the supplementary fuel flows through burner throat 24 andacross throat tile 25 into the combustion chamber 3. This mass ofburning supplementary fuel and air intersects the incoming streams oflow heat value fuel entering through ports 4 and initiates and maintainsits combustion. Combustion continues throughout the length of combustionchamber 3 to its exit.

Under some operating conditions it may become necessary to fire thefurnace completely with fuel through gas manifold 20, oil tip 22, gasgun 23 or nozzle 30. When this situation exists, it is desirable topressurize the gas plenum chamber 2 with air from wind-box 16. This airis transported through by-pass ducts 26, and is controlled by dampers27. Under these conditions of operation it may be necessary to admit airlongitudinally through ports 28, which are opened or closed by damperplate 29. The action of this air cools the refractory lining of thecombustion chamber and also pushes the ignition point further along inthe chamber.

Under some conditions, such as a full supply of low heat value fuel andan overload of supplementary fuel, the combustion chamber might reach anexcessive temperature. When this occurs, air is admitted longitudinallythrough ports 28 which are opened or closed by damper plate 29. Thisopening decreases the amount of air required to flow through register 17which has a turbulent rotary motion. At the same time the air movinglongitudinally through ports 28 and parallel with combustion chamberlining pushes the ignition point toward the combustion chamber exitwhich lowers the temperature of linings 8 and 14.

Another application of this burner is for utilizing hot waste gasconsisting mostly of hot air with some inert products of combustion suchas exhaust gas from a gas turbine. In this case any air for combustionwould be delivered to wind-box 16 through ducts 26 up to the limit ofair available from waste gases. If more air is required forsupplementary fuel fired through burner throat 24, it is provided by theusual fan through air plenum chamber 6. The usual condition is for morehot air and gas to be provided than is required for the supplementaryfuel fired through burner throat. If it is attempted to put all of thisexcess air through a burner throat, the supplementary flame will beextinguished. My invention provides means for putting only that portionneeded for combustion of supplementary fuel through the throat of theburner. A stable flame is accomplished and preserved before the mass offlame encounters the great amount of excess air in the hot waste gasentering through ports 4. Thus it becomes possible to utilize thesensible heat of the entire turbine exhaust without having it interferewith combustion of supplementary fuel.

Another application of this burner is for handling hogged wood waste andsander dust from sawmills and wood working facilities. Hogged fuelparticles suspended in air can be blown'through ports 4 instead ofgaseous fuels. Simultaneously aerated sander dust can be fired throughnozzle 30 instead of pulverized coal. This assures drying and burning ofwet wood chips producing a stable flame. This also provides a burningmass to discharge explosive sander dust into, thus assuring immediateignition.

This burner is completely controllable by means of the usual dampers andfuel control valves, Control can be manual or fully automatic.

What is claimed as new is:

1. In a furnace having a wind-box for combustion air at the front of thefurnace, a refractory lined combustion chamber extending axially fromthe wind-box, a supplementary fuel burner between the wind-box andcombustion chamber directing its flame axially into the combustionchamber, a register for supplying combustion air from the wind-box tothe supplementary fuel burner, means forming passageways for dischargingcombustion air from the wind-box axially along the lining, a combustionair chamber spaced from the front of the furnace, a passageway leadingfrom the combustion air chamber to the wind-box in heat exchangerelation to the combustion chamber, a plenum chamber for low heat valuefuel surrounding the combustion chamber, means forming passagewaysextending from the plenum chamber tangentially into the combustionchamber along its length and providing a rotating mass of low heat fuelsurrounding the supplementary burner flame, said flame intersect: ingthe rotating mass and initiating the combustion of the low heat valuefuel.

2. In a furnace having a front, a wind-box for combustion air at thefront of the furnace, spaced inner and outer metal shells extendingaxially from the wind-box, a refractory lining for the inner shellproviding a combustion chamber, said combustion chamber having a throatadjacent the wind-box, a supplementary fuel burner directing its flameaxially through the throat into the combustion chamber, a register forsupplying combustion air to the throat, means forming passageways fordischarging combustion air from the wind-box axially along the lining, acombustion air chamber spaced from the front of the furnace andcommunicating with the space between the shells, the inner end of thespace between the shells communicating with the wind-box, a plenumchamber for low heat value fuel surrounding the outer shell, meansforming passageways extending from the plenum chamber tangentially intothe combustion chamber along its length and providing a rotating mass oflow heat value fuel surrounding the supplementary fuel burner flame,said 4 flame intersecting the rotating mass and initiating thecombustion of the lowheat-valuefuel.

3. In a furnace having a wind-box for combustion air at the front of thefurnace, spaced inner and outer metal shells extending axially from thewind-box, a refractory lining for the inner shell providing a combustionchamber, said combustion chamber having a throat adjacent the wind-box,a supplementary fuel burner directing its flame axially through thethroat into the combustion chamber, a register for supplying combustionair to the throat, a combustion air chamber spaced from the front of thefurnace and communicating with the space between the shells, the innerend of the space between the shells communicating with the wind-box, aplenum chamber for low heat value fuel surrounding the outer shell,means forming passageways extending from the plenum chamber tangentiallyinto the combustion chamber along its length and providing a rotatingmass of low heat value fuel surrounding the burner flame, said flameintersecting the rotating mass and initiating the combustion of the lowheat value fuel.

4. In a furnace having a wind-box for combustion air at the front of thefurnace, spaced inner and outer shells extending axially from thewind-box the inner shell providing a combustion chamber and the spacebetween the shells providing a heat exchange passage for combustion aircommunicating with said wind-box, a burner for a first fuel having itsflame directed axially into the combustion chamber from the wind-box,means formin passageways extending tangentially into the combustionchamher along its length and for supplying a rotating mass of a secondfuel of low heat value surrounding the burner flame, said flameintersecting the rotating mass and initiating the combustion of the lowheat value fuel.

5. The burner of claim 4 in which the first fuel is wood sander dust andthe second fuel is wood waste particles.

References Cited by the Examiner UNITED STATES PATENTS Re. 25,08611/1961 Lotz 11028 1,795,347 3/1931 Reese 1l028 2,672,402 3/1954 Stokes158-11 2,986,206 5/1961 Boelsma 158ll 3,073,684 1/1964 Williams l5811FOREIGN PATENTS 576,932 4/ 1946 Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

MEYER PERLIN, Examiner.

1. IN A FURNACE HAVING A WIND-BOX FOR COMBUSTION AIR AT THE FRONT OF THEFURNACE, A REFRACTORY LINED COMBUSTION CHAMBER EXTENDING AXIALLY FROMTHE WIND-BOX A SUPPLEMENTARY FUEL BURNER BETWEEN THE WIND-BOX ANDCOMBUSTION CHAMBER DIRECTING ITS FLAME AXIALLY INTO THE COMBUSTIONCHAMBER, A REGISTER FOR SUPPLYING COMBUSTION AIR FROM THE WIND-BOX TOTHE SUPPLEMENTARY FUEL BURNER, MEANS FORMING PASSAGEWAYS FOR DISCHARGINGCOMBUSTION AIR FROM THE WIND-BOX AXIALLY ALONG THE LINING, A COMBUSTIONAIR CHAMBER SPACED FROM THE FRONT OF THE FURNACE, A PASSAGEWAY LEADINGFROM THE COMBUSTION AIR CHAMBER TO THE WIND-BOX IN HEAT EXCHANGERELATION TO THE COMBUSTION CHAMBER, A PLENUM CHAMBER FOR LOW HEAT VALUEFUEL SURROUNDING THE COMBUSTION CHAMBER, MEANS FORMING PASSAGEWAYSEXTENDING FROM THE PLENUM CHAMBER TANGENTIALLY INTO THE COMBUSTIONCHAMBER ALONG ITS LENGTH AND PROVIDING A ROTATING MASS OF LOW HEAT FUELSURROUNDING THE SUPPLEMENTARY BURNER FLAME, SAID FLAME INTERSECTING THEROTATING MASS AND INITIATING THE COMBUSTION OF THE LOW HEAT VALUE FUEL.